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// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.
package com.microsoft.azure.eventprocessorhost;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.ConcurrentHashMap;
/***
* An ILeaseManager implementation based on an in-memory store.
*
* THIS CLASS IS PROVIDED AS A CONVENIENCE FOR TESTING ONLY. All data stored via this class is in memory
* only and not persisted in any way. In addition, it is only visible within the same process: multiple
* instances of EventProcessorHost in the same process will share the same in-memory store and leases
* created by one will be visible to the others, but that is not true across processes.
*
* With an ordinary store, there is a clear and distinct line between the values that are persisted
* and the values that are live in memory. With an in-memory store, that line gets blurry. If we
* accidentally hand out a reference to the in-store object, then the calling code is operating on
* the "persisted" values without going through the manager and behavior will be very different.
* Hence, the implementation takes pains to distinguish between references to "live" and "persisted"
* checkpoints.
*
* To use this class, create a new instance and pass it to the EventProcessorHost constructor that takes
* ILeaseManager as an argument. After the EventProcessorHost instance is constructed, be sure to
* call initialize() on this object before starting processing with EventProcessorHost.registerEventProcessor()
* or EventProcessorHost.registerEventProcessorFactory().
*/
public class InMemoryLeaseManager implements ILeaseManager {
private static final Logger TRACE_LOGGER = LoggerFactory.getLogger(InMemoryLeaseManager.class);
private HostContext hostContext;
private long millisecondsLatency = 0;
public InMemoryLeaseManager() {
}
// This object is constructed before the EventProcessorHost and passed as an argument to
// EventProcessorHost's constructor. So it has to get context info later.
public void initialize(HostContext hostContext) {
this.hostContext = hostContext;
}
public void setLatency(long milliseconds) {
this.millisecondsLatency = milliseconds;
}
private void latency(String caller) {
if (this.millisecondsLatency > 0) {
try {
//TRACE_LOGGER.info("sleep " + caller);
Thread.sleep(this.millisecondsLatency);
} catch (InterruptedException e) {
// Don't care
TRACE_LOGGER.info("sleepFAIL " + caller);
}
}
}
@Override
public int getLeaseDurationInMilliseconds() {
return this.hostContext.getPartitionManagerOptions().getLeaseDurationInSeconds() * 1000;
}
@Override
public CompletableFuture leaseStoreExists() {
boolean exists = InMemoryLeaseStore.SINGLETON.existsMap();
latency("leaseStoreExists");
TRACE_LOGGER.debug(this.hostContext.withHost("leaseStoreExists() " + exists));
return CompletableFuture.completedFuture(exists);
}
@Override
public CompletableFuture createLeaseStoreIfNotExists() {
TRACE_LOGGER.debug(this.hostContext.withHost("createLeaseStoreIfNotExists()"));
InMemoryLeaseStore.SINGLETON.initializeMap(getLeaseDurationInMilliseconds());
latency("createLeaseStoreIfNotExists");
return CompletableFuture.completedFuture(null);
}
@Override
public CompletableFuture deleteLeaseStore() {
TRACE_LOGGER.debug(this.hostContext.withHost("deleteLeaseStore()"));
InMemoryLeaseStore.SINGLETON.deleteMap();
latency("deleteLeaseStore");
return CompletableFuture.completedFuture(null);
}
@Override
public CompletableFuture getLease(String partitionId) {
TRACE_LOGGER.debug(this.hostContext.withHost("getLease()"));
latency("getLease");
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(partitionId);
return CompletableFuture.completedFuture(new InMemoryLease(leaseInStore));
}
@Override
public CompletableFuture> getAllLeases() {
ArrayList infos = new ArrayList();
for (String id : InMemoryLeaseStore.SINGLETON.getPartitionIds()) {
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(id);
infos.add(new BaseLease(id, leaseInStore.getOwner(), !leaseInStore.isExpiredSync()));
}
latency("getAllLeasesStateInfo");
return CompletableFuture.completedFuture(infos);
}
@Override
public CompletableFuture createAllLeasesIfNotExists(List partitionIds) {
ArrayList> createFutures = new ArrayList>();
// Implemented like this to provide an experience more similar to lease creation in the Storage-based manager.
for (String id : partitionIds) {
final String workingId = id;
CompletableFuture oneCreate = CompletableFuture.supplyAsync(() -> {
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(workingId);
InMemoryLease returnLease = null;
if (leaseInStore != null) {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(workingId,
"createLeaseIfNotExists() found existing lease, OK"));
returnLease = new InMemoryLease(leaseInStore);
} else {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(workingId,
"createLeaseIfNotExists() creating new lease"));
InMemoryLease newStoreLease = new InMemoryLease(workingId);
InMemoryLeaseStore.SINGLETON.setOrReplaceLease(newStoreLease);
returnLease = new InMemoryLease(newStoreLease);
}
latency("createLeaseIfNotExists " + workingId);
return returnLease;
}, this.hostContext.getExecutor());
createFutures.add(oneCreate);
}
CompletableFuture[] dummy = new CompletableFuture[createFutures.size()];
return CompletableFuture.allOf(createFutures.toArray(dummy));
}
@Override
public CompletableFuture deleteLease(CompleteLease lease) {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(lease, "deleteLease()"));
InMemoryLeaseStore.SINGLETON.removeLease((InMemoryLease) lease);
latency("deleteLease " + lease.getPartitionId());
return CompletableFuture.completedFuture(null);
}
@Override
public CompletableFuture acquireLease(CompleteLease lease) {
InMemoryLease leaseToAcquire = (InMemoryLease) lease;
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToAcquire, "acquireLease()"));
boolean retval = true;
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(leaseToAcquire.getPartitionId());
if (leaseInStore != null) {
InMemoryLease wasUnowned = InMemoryLeaseStore.SINGLETON.atomicAquireUnowned(leaseToAcquire.getPartitionId(), this.hostContext.getHostName());
if (wasUnowned != null) {
// atomicAcquireUnowned already set ownership of the persisted lease, just update the live lease.
leaseToAcquire.setOwner(this.hostContext.getHostName());
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToAcquire,
"acquireLease() acquired lease"));
leaseInStore = wasUnowned;
leaseToAcquire.setExpirationTime(leaseInStore.getExpirationTime());
} else {
if (leaseInStore.isOwnedBy(this.hostContext.getHostName())) {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToAcquire,
"acquireLease() already hold lease"));
} else {
String oldOwner = leaseInStore.getOwner();
// Make change in both persisted lease and live lease!
InMemoryLeaseStore.SINGLETON.stealLease(leaseInStore, this.hostContext.getHostName());
leaseToAcquire.setOwner(this.hostContext.getHostName());
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToAcquire,
"acquireLease() stole lease from " + oldOwner));
}
long newExpiration = System.currentTimeMillis() + getLeaseDurationInMilliseconds();
// Make change in both persisted lease and live lease!
leaseInStore.setExpirationTime(newExpiration);
leaseToAcquire.setExpirationTime(newExpiration);
}
} else {
TRACE_LOGGER.warn(this.hostContext.withHostAndPartition(leaseToAcquire,
"acquireLease() can't find lease"));
retval = false;
}
latency("acquireLease " + lease.getPartitionId());
return CompletableFuture.completedFuture(retval);
}
// Real partition pumps get "notified" when another host has stolen their lease because the receiver throws
// a ReceiverDisconnectedException. It doesn't matter how many hosts try to steal the lease at the same time,
// only one will end up with it and that one will kick the others off via the exclusivity of epoch receivers.
// This mechanism simulates that for dummy partition pumps used in testing. If expectedOwner does not currently
// own the lease for the given partition, then notifier is called immediately, otherwise it is called whenever
// ownership of the lease changes.
public void notifyOnSteal(String expectedOwner, String partitionId, Callable notifier) {
InMemoryLeaseStore.SINGLETON.notifyOnSteal(expectedOwner, partitionId, notifier);
}
@Override
public CompletableFuture renewLease(CompleteLease lease) {
InMemoryLease leaseToRenew = (InMemoryLease) lease;
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToRenew, "renewLease()"));
boolean retval = true;
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(leaseToRenew.getPartitionId());
if (leaseInStore != null) {
// MATCH BEHAVIOR OF AzureStorageCheckpointLeaseManager:
// Renewing a lease that has expired succeeds unless some other host has grabbed it already.
// So don't check expiration, just ownership.
if (leaseInStore.isOwnedBy(this.hostContext.getHostName())) {
long newExpiration = System.currentTimeMillis() + getLeaseDurationInMilliseconds();
// Make change in both persisted lease and live lease!
leaseInStore.setExpirationTime(newExpiration);
leaseToRenew.setExpirationTime(newExpiration);
} else {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToRenew,
"renewLease() not renewed because we don't own lease"));
retval = false;
}
} else {
TRACE_LOGGER.warn(this.hostContext.withHostAndPartition(leaseToRenew,
"renewLease() can't find lease"));
retval = false;
}
latency("renewLease " + lease.getPartitionId());
return CompletableFuture.completedFuture(retval);
}
@Override
public CompletableFuture releaseLease(CompleteLease lease) {
InMemoryLease leaseToRelease = (InMemoryLease) lease;
CompletableFuture retval = CompletableFuture.completedFuture(null);
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToRelease, "releaseLease()"));
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(leaseToRelease.getPartitionId());
if (leaseInStore != null) {
if (!leaseInStore.isExpiredSync() && leaseInStore.isOwnedBy(this.hostContext.getHostName())) {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToRelease, "releaseLease() released OK"));
// Make change in both persisted lease and live lease!
leaseInStore.setOwner("");
leaseToRelease.setOwner("");
leaseInStore.setExpirationTime(0);
leaseToRelease.setExpirationTime(0);
}
} else {
TRACE_LOGGER.warn(this.hostContext.withHostAndPartition(leaseToRelease, "releaseLease() can't find lease in store"));
retval = new CompletableFuture();
retval.completeExceptionally(new CompletionException(new RuntimeException("releaseLease can't find lease in store for " + leaseToRelease.getPartitionId())));
}
latency("releaseLease " + lease.getPartitionId());
return retval;
}
@Override
public CompletableFuture updateLease(CompleteLease lease) {
InMemoryLease leaseToUpdate = (InMemoryLease) lease;
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToUpdate, "updateLease()"));
// Renew lease first so it doesn't expire in the middle.
return renewLease(leaseToUpdate).thenApply((retval) -> {
if (retval) {
InMemoryLease leaseInStore = InMemoryLeaseStore.SINGLETON.getLease(leaseToUpdate.getPartitionId());
if (leaseInStore != null) {
if (!leaseInStore.isExpiredSync() && leaseInStore.isOwnedBy(this.hostContext.getHostName())) {
// We are updating with values already in the live lease, so only need to set on the persisted lease.
leaseInStore.setEpoch(leaseToUpdate.getEpoch());
// Don't copy expiration time, that is managed directly by Acquire/Renew/Release
} else {
TRACE_LOGGER.debug(this.hostContext.withHostAndPartition(leaseToUpdate,
"updateLease() not updated because we don't own lease"));
retval = false;
}
} else {
TRACE_LOGGER.warn(this.hostContext.withHostAndPartition(leaseToUpdate,
"updateLease() can't find lease"));
retval = false;
}
}
latency("updateLease " + lease.getPartitionId());
return retval;
});
}
private static class InMemoryLeaseStore {
static final InMemoryLeaseStore SINGLETON = new InMemoryLeaseStore();
private volatile int leaseDurationInMilliseconds;
private ConcurrentHashMap inMemoryLeasesPrivate = null;
private ConcurrentHashMap> notifiers = new ConcurrentHashMap>();
synchronized boolean existsMap() {
return (this.inMemoryLeasesPrivate != null);
}
synchronized void initializeMap(int leaseDurationInMilliseconds) {
if (this.inMemoryLeasesPrivate == null) {
this.inMemoryLeasesPrivate = new ConcurrentHashMap();
}
this.leaseDurationInMilliseconds = leaseDurationInMilliseconds;
}
synchronized void deleteMap() {
this.inMemoryLeasesPrivate = null;
}
synchronized InMemoryLease getLease(String partitionId) {
return this.inMemoryLeasesPrivate.get(partitionId);
}
synchronized List getPartitionIds() {
ArrayList ids = new ArrayList();
this.inMemoryLeasesPrivate.keySet().forEach((key) -> {
ids.add(key);
});
return ids;
}
synchronized InMemoryLease atomicAquireUnowned(String partitionId, String newOwner) {
InMemoryLease leaseInStore = getLease(partitionId);
if (leaseInStore.isExpiredSync() || (leaseInStore.getOwner() == null) || leaseInStore.getOwner().isEmpty()) {
leaseInStore.setOwner(newOwner);
leaseInStore.setExpirationTime(System.currentTimeMillis() + this.leaseDurationInMilliseconds);
} else {
// Return null if it was already owned
leaseInStore = null;
}
return leaseInStore;
}
synchronized void notifyOnSteal(String expectedOwner, String partitionId, Callable notifier) {
InMemoryLease leaseInStore = getLease(partitionId);
if (!leaseInStore.isOwnedBy(expectedOwner)) {
// Already stolen.
try {
notifier.call();
} catch (Exception e) {
TRACE_LOGGER.warn("notifier call failed: " + e.getMessage());
}
} else {
this.notifiers.put(partitionId, notifier);
}
}
synchronized void stealLease(InMemoryLease stealee, String newOwner) {
stealee.setOwner(newOwner);
Callable notifier = this.notifiers.get(stealee.getPartitionId());
if (notifier != null) {
try {
notifier.call();
} catch (Exception e) {
TRACE_LOGGER.warn("notifier call failed: " + e.getMessage());
}
}
}
synchronized void setOrReplaceLease(InMemoryLease newLease) {
this.inMemoryLeasesPrivate.put(newLease.getPartitionId(), newLease);
}
synchronized void removeLease(InMemoryLease goneLease) {
this.inMemoryLeasesPrivate.remove(goneLease.getPartitionId());
}
}
private static class InMemoryLease extends CompleteLease {
private static final Logger TRACE_LOGGER = LoggerFactory.getLogger(InMemoryLease.class);
private long expirationTimeMillis = 0;
InMemoryLease(String partitionId) {
super(partitionId);
this.epoch = 0;
}
InMemoryLease(InMemoryLease source) {
super(source);
this.expirationTimeMillis = source.expirationTimeMillis;
this.epoch = source.epoch;
}
long getExpirationTime() {
return this.expirationTimeMillis;
}
void setExpirationTime(long expireAtMillis) {
this.expirationTimeMillis = expireAtMillis;
}
public boolean isExpiredSync() {
boolean hasExpired = (System.currentTimeMillis() >= this.expirationTimeMillis);
TRACE_LOGGER.debug("isExpired(" + this.getPartitionId() + (hasExpired ? ") expired " : ") leased ") + (this.expirationTimeMillis - System.currentTimeMillis()));
return hasExpired;
}
@Override
public boolean equals(Object o) {
return super.equals(o);
}
@Override
public int hashCode() {
return super.hashCode();
}
}
}
